The objective of this study is to examine specific and non-specific activation of both T and B lymphocytes at the cellular and cell surface level. The activation signals to be studied are antigen and/or mitogen induced positive and negative signals for B cells and events associated with the activation of T lymphocytes in vivo and in vitro. These objectives will be approached using in vitro tissue culture techniques and coordinate examination of distribution of antigen receptors of the B cells under the influence of both positive and negative aspects of the immune response. The induction of an in vitro induced specific unresponsiveness will be examined at the cell receptor levels as well as the mechanism of induction and removal of this specific unresponsiveness.